The effect of PUVA therapy on pruritus, the skin mast cell population and histamine metabolism has been studied in 3 patients with urticaria pigmentosa and manifestations of systemic mastocytosis. ...Relief of itch was found concomitant with a significant decrease of the major histamine metabolite 1-methyl-4-imidazoleacetic acid in the urine. The decrease occurred during the first 2 mo after starting PUVA therapy and was sustained during an observation period of 3 mo after discontinuation of the treatment. At this time a reduction of the number of mast cells was found in skin biopsy specimens. No evidence of acute histamine release in association with PUVA treatment was obtained. These results suggest that this effective new treatment for urticaria pigmentosa reduces the histamine turnover in the skin by inhibiting mast cell proliferation.
Bullous mastocytosis (diffuse cutaneous mastocytosis) is a rare form of mast cell disease that begins during the first month of life and causes extensive blisters that mimic scalded skin syndrome or ...bullous erythema multiforme. Discrete pigmented macules, papules, and nodules are absent and the characteristic leathery induration of skin may not develop until 6 months of age. Skin biopsy shows a subepidermal blister with mast cells at the base. The most serious complications are gastrointestinal hemorrhage and shock. The symptoms of bullous mastocytosis may be modified by a number of new therapeutic agents.
The Authors describe four cases of cutaneous mastocytosis observed during paediatric age. They notice that the disease presents itself with a clinical polymorphous situation which sometimes exceeds ...the limits of the cutaneous gambit, until the illness reveals itself a systemic serious disease. Besides they point out uncertain etiopathogenesis, the utility of a correct diagnostic approach and the utility of a therapy which is continually in evolution.
The diagnosis of systemic mastocytosis depends on the proper recognition of extensive mast cells infiltration in tissues. Accurate identification of the mast cells in tissues may be difficult when ...there is no clinical suspicion to initiate a special search for these cells. Four patients with atypical clinical features and eosinophilia in tissues and three with eosinophilia in blood had hematologic or histologic findings suggestive of myelofibrosis with myeloid metaplasia, and malignant lymphoma. It was the presence of blood and tissue eosinophilia in these patients that led to further investigation and recognition of the diagnosis of systemic mastocytosis. Methods for identification of the mast cells are examined. The combined use of Wright-Giemsa stain, toluidine blue, and aminocaproate esterase is preferred. The eosinophils are intimately related to the mast cells. In cases of eosinophilia of unknown etiology, systemic mastocytosis should be considered one of the possible etiologic factors.
Human eosinophils contain several distinctive proteins including eosinophil granule MBP and the membrane-associated CLC protein (lysophospholipase). Human basophils also contain these proteins, ...indicating biochemical similarities between eosinophils and basophils. To determine whether MBP or CLC protein is present in connective tissue mast cells, we studied human lung and cutaneous mast cells by immunofluorescence by utilizing specific antibodies to CLC and MBP. Cytocentrifuge slides of enriched lung mast cells and mast cells in sections of formalin-fixed, paraffin-embedded cutaneous tissue from urticaria pigmentosa lesions were stained for CLC and MBP. Neither pulmonary nor cutaneous mast cells stained for CLC protein or MBP. In contrast, lung and cutaneous eosinophils in the same preparations showed bright staining for both proteins. The failure to find CLC protein and MBP in mast cells provides additional evidence of dissimilarity between mast cells and basophils, and an immunochemical means to distinguish between them.
The authors describe one case of urticaria pigmentosa in childhood as contribution to the knowledge of this disease prevalently interesting the paediatric dermatology.
Human connective tissue type mast cells (CTMC) are frequently located in close proximity to microvascular and neural basement membranes (BM). We have explored the interaction between human dermal ...connective tissue-type (chymase positive) mast cells and laminin, a component of BM. In this report, we document that normal CTMC express laminin receptors and are intimately associated with laminin of BM in vivo and pericellular laminin complexes in vitro. Upon degranulation in vitro, CTMC-laminin complexes dissociate and CTMC do not adhere to laminin substrates. In cutaneous mastocytosis/urticaria pigmentosa, CTMC do not express laminin receptors detectable by immunohistochemistry, and are frequently not in close association with laminin of vascular BM. These same features could be induced by degranulation of normal mast cells in organ culture. These findings indicate that CTMC-laminin interactions may be important determinants of mast cell localization in tissue compartments.
Two related Sphinx cats, the mother and her daughter, showed pruritic maculae and pigmented papules, which correspond to those of urticaria pigmentosa in humans. The skin lesions in both cases were ...juvenile onset, and histopathological examination revealed diffuse infiltration of well-differentiated mast cells at the dermis. The lesions were resolved with antihistamines.
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